The invention pertains to a roller drive unit with:
a roller PA1 a motor to drive the roller PA1 a drive shaft coupled to the motor PA1 a gear system to couple the roller to the drive shaft whereby the gear system has: PA1 a support element on which the roller is supported in a rotary manner and which is in turn rotatable about the axis of the roller, PA1 a device for limiting the angular range about which the support element rotates and PA1 a supporting device for receiving the force acting by means of a load on the roller.
a drive gear coupled in a non-rotating manner to the drive shaft and PA2 a driven gear coupled to the roller on the one hand and to the drive gear on the other
Roller drive units similar to this are known. Such roller drive units are used, for example, for conveying freight holders which are placed on roller conveyors. Such freight holders can be containers or pallets. A preferred field of application for the roller drive unit shown is a freight-loading system in air freight traffic in which the containers are driven into the cargo space of an aircraft and are stowed there. The roller drive unit is accordingly installed in the aircraft itself.
An example of a known roller drive unit is shown in DE-C-3 911 214 (U.S. Pat. No. 5,048,672). The known roller drive unit uses a swivel element as a basic supporting feature. This swivel element supports the roller. The swivel element is supported by the drive shaft and the drive shaft is supported by the frame. With this type of arrangement the driving forces are carried through the drive shaft to the aircraft structure.
To raise the roller the swivel element is rotated around the drive shaft. The roller rises due to the eccentric location of the drive shaft. The transfer of drive forces therefore transmits an undesirable bending moment to the drive shaft.
A similar roller drive unit is described in DE-C-3 724 126. Here the stator supports the roller. It is swivel mounted and swings around the axle to raise the roller. Also here the driving forces are carried to the frame through the drive shaft.
From DE-C-4 336 978 another power drive roller is known which increases the vertical force of the roller by using the reaction force of the planetary gear to depress a spring thereby transferring the driving forces to the structure.